A powered suit (or powered armor) that is set up to save as much of your body as possible in worse case scenarios.

When fighting in space, it is essential to close off damaged parts of a space suit to save the rest of the body.

"The suit is set up to save as much of your body as possible. If you lose part of an arm or a leg, one of sixteen razor-sharp irises closes around your limb with the force of a hydraulic press, snipping it off neatly and sealing the suit before you can die of explosive decompression. Then "trauma maintenance" cauterizes the stump, replaces lost blood,and fills you full of happy juice and No-shock. So you will either die happy or, if your comrades go on to win the battle, eventually be carried back up to the ship's aid station."

I stripped and backed into the clamshelled suit. The new ones were a hell of a lot more complicated, with all the new biometrics and trauma maintenance. But well worth the trouble of hooking up, in case you got blown apart just a little bit. Go home to a comfortable pension with heroic prostheses. They were even talking about the possibility of regeneration, at least for missing arms and legs...

Thanks to an anonymous reader for suggesting this item, and supplying the quote.